Background Assumptions of the CA

Onotological Assumption: that existence has meaning, and that 'God' is the best explanation for why there is something rather than nothing.

Epistemological Assumption: that we can have knowledge about the origins of the universe.

Semantical Assumption: it is sometimes argues that the CA derives an actual explanation of the world from a possible one, i.e. 'possible' becomes semantically equivelant to 'actual' so the statement 'God is a possible first cause of the universe' becomes 'God is the actual first cause of the universe'.

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Aquinas' Argument in Aristotle's Philosophy

Aquinas was heavily influenced by the teachings of Aristotle who taught that everything that exists can be explained by 4 causes (matter, form, efficient cause and the final cause/purpose).

By 'cause' Aristotle means 'explanation', only the 'cause' in 'efficient cause' means what we understand 'cause' to mean.

Aristotle also argued that the 4 causes themselves needed to be explained - what begins the process of motion and change? His answer was that there must be a First Efficient Cause, which he calls the Prime Mover.

The Prime Mover cannot be made of matter, otherwise it would need an efficient cause, so the Prime Mover must be non-material and exist outside space and time.

This Prime Mover did not beng motion and change with some kind of 'push' like a domino effect, but rather by being a perfect Final Cause which all things are attracted to because of its perfection.

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Aquinas' Argument in Observation

The CA is an a posteriori argument - meaning it is based on observation.

Aquinas' CA is based on 3 main observations:

- That things move and are changed

- That things in the world are subject to the laws of cause and effect

- That the universe is contingent

Aquinas argues back from these observations to the supopsed cause of them - the conclusion is that there must be a being who created the universe and who is the source of movement and change.

"God's effects are enough to prove that God exists, even if they may not be enough to help us comprehend what He is." - Aquinas; 'Summa Theologica'

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Aquinas' First Way: The Argument from Motion

In the Summa Theologica Aquinas develops 5 arguements (5 'Ways') for the existence of God. The first 3 of these are the CA.

The First Way - The Argument from Motion:P1 - some things are in motion, others are at restP2 - something at rest is in a state of potentialP3 - something potential can be moved only by something actualP4 - If matter cannot move itself, then we have no explanation for why some things are now in motionP5 - there cannot be an infinite chain of past movers; otherwise there would be no motion nowC1 - so there must have been a First Unmoved MoverC2 - This was God

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The Second Way: The Argument from Efficient Cause

P1 - there is an efficient cause for everythingP2 - nothing can be the efficient cause of itselfP3 - there cannot be an infinite regress of efficient causes; otherwise there would be no explanation of the presentC1 - so there must be an Uncaused Cause, which causes everything to happen but is not caused itselfC2 - this is God

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The Third Way: The Argument from Contingency and N

P1 - everything is contingentP2 - then at some point there was nothing, because there must have been a time when nothing had begun to existP3 - If there was once nothing, nothing could come from itP4 - therefore something must exist necessarily, otherwise nothing would exist nowP5 - everything necessary must either be caused or uncausedP6 - the series of necessary being cannot be inifinite, or there would be no explanation of the seriesC1 - therefore there must be some uncaused being which has necessary existenceC2 - this is God